The objectives of this research are as follows: To delineate the ultrastructure of the normal microcirculation in human skin. Microcirculation is defined to include both blood and lymphatic vessels. Lymphatic vessels will be identified by the uptake of colloidal carbon injected intradermally. Psoriatic lesions in various stages of development and regression will be studied by electron microscopy to determine the nature of the vascular abnormalities noted by light microscopy, and whether these abnormalities precede or come after the epidermal hyperplasia of the disease. Telangiectasias of various types which indicate the presence of a systemic disease will be studied to determine their three dimensional configurations by cleared whole mounts of skin. The type of abnormal vessel present in the malformation will be studied by electron microscopy.